Method and apparatus for memory redundancy in a microprocessor

ABSTRACT

An apparatus for redundancy of a memory array includes a primary memory array including a plurality of memory cells, one or more of which are defective. A redundant array includes a CAM array that includes a plurality of memory cells. The CAM array is addressed by the address of a defective memory location within the primary memory array and provides a match identification and a resource identification. The redundant array also includes a translation array wherein an offset to configure an input/output multiplexer is stored. The redundant array also includes a redundant data array including a plurality of memory cells wherein one or more memory cells of the redundant data array are used instead of one or more defective memory cells of the primary array.

BACKGROUND

Modern microprocessors may include one or more cores that are capable ofperforming operations typically associated with a traditional centralprocessing unit (CPU).

Referring to FIG. 1, a multi-core microprocessor 100 is shown, whichcomprises one or more die 120 disposed in a mechanical package 110. Eachdie is comprised of one or more cores 130, one or more primary cachememory arrays 140, one or more secondary cache memory arrays 150, andadditional circuitry and connectivity necessary for the proper operationof the microprocessor.

The cache memory arrays comprise a plurality of cache lines comprised ofa plurality of bits that are used to store previously accessedinstructions or data. Cache memory arrays are typically comprised offast Static Random Access Memory (SRAM). Cache memory arrays aredifferentiated by their place in the hierarchical organization of memorywithin a system. For example, level one (L1) refers to small instructionand/or data cache memory arrays disposed on the microprocessor die andlevel two (L2) refers to larger instruction and/or data cache memoryarrays also disposed on the microprocessor die, but further removed fromthe core than L1. It is well understood in the art that the hierarchicalorganization of memory and the use of cache memory arrays reduces mainmemory latency and improves system performance.

Single-core microprocessors typically have dedicated L1 and L2instruction and data caches disposed on die. Multi-core microprocessorstypically have a mix of dedicated and shared cache memory arrays. Forexample, Sun Microsystems' high end microprocessor is comprised of fourcore clusters, each comprised of four cores, resulting in sixteen totalcores. Each core within a given core cluster shares L1 instruction anddata caches and all core clusters share L2 instruction and data caches.One of ordinary skill in the art will recognize that there are a numberof ways in which to organize cache memory arrays disposed in amicroprocessor.

Application Specific Integrated Circuits (ASICs), Field-ProgrammableGate Arrays (FPGAs), and other semiconductor devices are also comprisedof memory arrays utilized for a variety of purposes.

The fabrication of a semiconductor device comprised of a memory array iscomplicated by defects that are inherent in the fabrication process.There may be a number of defective memory cells within the memory array.Additionally, there may be a number of memory cells that fail to meetminimum electrical requirements and are deemed to be defective. Thesedefects could be a single defective memory cell or multiple defectivememory cells. Multiple defective memory cells may be present in a givenrow and/or column of the memory array. Multiple defective memory cellsmay span one or more rows and/or one or more columns of the memoryarray.

Accordingly, certain redundancy schemes have utilized banks of fuses todisable defective cells and enable redundant cells. In post fabricationprocessing, the defective cells are disabled and redundant cells areenabled through the use of a laser, banks of fuses, and relatedcircuitry. Typically, two banks of fuses are required. A first bank offuses is utilized to disable defective cells. Defective cells aredisabled by triggering one or more fuses with a laser to create opencircuits. A second bank of fuses is utilized to enable redundant cells.Redundant cells are enabled by triggering one or more fuses with a laserto create bridge circuits. Other prior art redundancy schemes haveutilized shift registers.

SUMMARY

According to one aspect of one or more embodiments of the presentinvention, an apparatus for redundancy of a memory array comprising: aprimary memory array comprising a plurality of memory cells wherein oneor more memory cells of the primary array are defective; a redundantarray comprising: a CAM array comprising a plurality of memory cells,wherein the addresses of the one or more defective memory locationswithin the primary array are stored, wherein the CAM array is addressedby the addresses of the one or more defective memory locations withinthe primary memory array, and wherein the CAM array provides a matchidentification to a translation array and a resource identification to aredundant data array, the translation array, wherein an offset thatconfigures an input/output multiplexer is stored, wherein thetranslation array provides the offset to the input/output multiplexer,the redundant data array comprising a plurality of memory cells, whereinone or more memory cells of the redundant data array are used instead ofone or more defective memory cells of the primary array; and theinput/output multiplexer wherein the input/output multiplexerselectively presents data comprised of data from or to the primarymemory array or data from or to the primary memory array and theredundant array.

According to one aspect of one or more embodiments of the presentinvention, a method for configuring a redundant array for redundancy ofa memory array comprising: identifying a defective memory cell within aprimary memory array; storing an address corresponding to the address ofthe defective memory cell within the primary memory array in a CAMarray; storing a match identification corresponding to the address ofthe defective memory cell within the primary memory array in the CAMarray; storing a resource identification corresponding to the matchidentification in the CAM array; and storing an offset corresponding tothe resource identification in a translation array.

According to one aspect of one or more embodiments of the presentinvention, a method for redundancy of a memory array comprising:presenting an address of a memory location within a primary memory arrayto the primary memory array; presenting the address of the memorylocation within the primary memory array to a redundant array whereinthe redundant array is comprised of a CAM array, a translation array,and a redundant data array; determining whether the address of thememory location within the primary memory array corresponds to adefective memory location within the primary memory array; if theaddress of the memory location within the primary memory arraycorresponds to the defective memory location within the primary memoryarray, presenting a match identification from the CAM array to thetranslation array, presenting a resource identification from the CAMarray to the redundant data array, presenting an offset that correspondsto the resource identification from the translation array to aninput/output multiplexer, configuring the input/output multiplexer inaccordance with the offset, performing a read or write operation inaccordance with the address of the memory location within the primarymemory array to the redundant data array; performing the read or a writeoperation in accordance with the address of the memory location withinthe primary memory array to the primary memory array; and presentingdata corresponding to the address of the memory location within theprimary memory array in accordance with the read or write operation.

Other aspects of the present invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a microprocessor comprised of a plurality of memory arrays.

FIG. 2 shows an apparatus for redundancy of a memory array in accordancewith an embodiment of the present invention.

FIG. 3 shows an apparatus for column redundancy of a memory array inaccordance with an embodiment of the present invention.

FIG. 4 shows an apparatus for row redundancy of a memory array inaccordance with an embodiment of the present invention.

FIG. 5 shows an apparatus for column and row redundancy of a memoryarray in accordance with an embodiment of the present invention.

FIG. 6 shows a method of configuring a redundant array for redundancy ofa memory array in accordance with an embodiment of the presentinvention.

FIG. 7 shows a method for redundancy of a memory array in accordancewith an embodiment of the present invention.

FIG. 8 shows an apparatus for column and row redundancy of a memoryarray disposed in a system in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION

Specific embodiments of the present invention will now be described indetail with reference to the accompanying figures. Like elements in thevarious figures are denoted by like reference numerals for consistency.Further, in the following detailed description of embodiments of thepresent invention, numerous specific details are set forth in order toprovide a more thorough understanding of the present invention. In otherinstances, well-known features have not been described in detail toavoid obscuring the description of embodiments of the present invention.

FIG. 2 shows an apparatus for redundancy of a memory array in accordancewith one or more embodiments of the present invention.

A primary memory array 200 is comprised of a plurality of memory cells.One or more memory cells of the primary memory array 200 may bedefective. Thus, a redundant array 220 comprised of acontent-addressable memory (CAM) array 225, a translation array 230, anda redundant data array 250 and an input/output multiplexer 210 comprisedof a plurality of multiplexers is also included. The CAM array 225 isconfigured to store defective memory cell locations within the primarymemory array 200 and other data necessary as part of the redundancyscheme described in detail below. The translation array 230 isconfigured to store offset 250 in accordance with the defective memorycell locations stored in the CAM array 225. The translation array 230could be a register file. An address 260 of a memory location within theprimary memory array 200 is presented to the primary memory array 200and the redundant array 220 as part of a read or a write operation.

In the case of the read operation (from primary memory), the primarymemory array 200 outputs data 270 to the input/output multiplexer 210 inaccordance with the address 260 of the memory location within theprimary memory array 200. If the address 260 of the memory locationwithin the primary memory array 200 is present in the CAM array 225, theCAM array 225 presents a match identification 240 to the translationarray 230 and a resource identification 245 to the redundant data array235. The resource identification 245 may be the match identification240. The translation array 230 presents an offset 250 to theinput/output multiplexer 210 in accordance with the match identification240. The redundant data array 235 utilizes the resource identification245 and the address 260 of the memory location within the primary memoryarray 200 to output data 255 to the input/output multiplexer 210 inaccordance with the read operation. The input/output multiplexer 210utilizes the offset 250, data 270 from the primary memory array 200, anddata 255 from the redundant data array 235 to output composite data 280.Composite data 280 is composed of data 270 or a combination of a subsetof data 270 and data 255 in accordance with the offset 250.

In the case of a write operation (to primary memory), data 270 is inputdirectly to the primary memory array 200 and composite data 280 is inputto the input/output multiplexer 210 in accordance with the address 260of the memory location within the primary memory array 200. Compositedata 280 is data 270 for the purpose of the write operation. If theaddress 260 of the memory location within the primary memory array 200is present in the CAM array 225, the CAM array 225 presents the matchidentification 240 to the translation array 230 and the resourceidentification 245 to the redundant data array 235. The translationarray 230 utilizes the match identification 240 to present the offset250 to the input/output multiplexer 210. The input/output multiplexer210 utilizes the offset 250 to selectively output a subset of compositedata 280 to the redundant data array 235. The redundant data array 235utilizes the resource identification 245 and the address 260 of thememory location within the primary memory array 200 to input data 255from the input/output multiplexer 210 to the redundant data array 235 inaccordance with the write operation.

FIG. 3 shows an apparatus for column redundancy of a memory array inaccordance with one or more embodiments of the present invention.

A primary memory array 300 is comprised of a plurality of memory cells.The primary memory array 300 could be organized as a 1024-line,64-bits-per-line, 8-way cache array. One of ordinary skill in the artwill appreciate that a set-associative cache scheme divides a cachearray into equal sections called ways that each function as a smalldirect-mapped cache array. The primary memory array 300 could belogically divided into a plurality of sub-blocks 302 of 128-lines,128-bits-per-line arrays. One or more memory cells of the primary memoryarray 300 may be defective. Thus, a redundant array 305 comprised of aCAM array 310, a translation array 315, and a redundant data array 320and an input/output multiplexer 325 is also included.

The CAM array 310 is organized as a 4-line, 6-bits-per-line array. TheCAM array 310 is configured to store defective memory cell locationswithin the primary memory array 300 and other data necessary as part ofthe redundancy scheme described in detail below. The translation array315 is organized as a 4-line, 8-bits-per-line array in a one hot encodedconfiguration. The translation array 315 is configured to store offset370 in accordance with the defective memory cell locations stored in theCAM array 310. As such, the translation array 315 provides an offset 370to the input/output multiplexer 325 that selects one of eight sets of8-bits in the 64-bit row. The translation array 315 could be a registerfile. The redundant data array 320 is organized as a 4-resource,128-lines-per-resource, 8-bits-per-line array. An input/outputmultiplexer 325 is comprised of an input multiplexer 335 and an outputmultiplexer 330. One of ordinary skill in the art will appreciate thatthe primary memory array 300, sub-blocks 302, CAM array 310, translationarray 315, and redundant data array 320 could be organized in variousother manners in accordance with one or more embodiments of the presentinvention.

An address of a memory location within the primary memory array 300 iscomprised of 13-bits that could be logically divided into three groups,ADDR[9:3] 340, ADDR[2:0] 345, and WAY[2:0] 350, to clarify the operationof one or more embodiments of the present invention. The 10-bitsrepresented by ADDR[9:3] 340 and ADDR[2:0] 345 can uniquely identify oneof the 1024 lines of the primary memory array 300. The 3-bitsrepresented by WAY[2:0] 350 can uniquely identify one of the eight waysof the primary memory array 300. The address, ADDR[9:3] 340, ADDR[2:0]345, and WAY[2:0] 350, of the memory location within the primary memoryarray 300 is presented to the primary memory array 300 as part of a reador write operation. A portion, ADDR[2:0] 345 and WAY[2:0] 350, of theaddress of the memory location within the primary memory array 300 ispresented to the CAM array 310 as part of the read or write operation. Aportion, ADDR[9:3] 340, of the address of the memory location within theprimary memory array 300 is presented to the redundant data array 320 aspart of the read or write operation.

In the case of the read operation, the primary memory array 300 outputs64-bits of data 365 to the output multiplexer 330 in accordance with theaddress, ADDR[9:3] 340, ADDR[2:0] 345, and WAY[2:0] 350, of the memorylocation within the primary memory array 300. If a portion, ADDR[2:0]345 and WAY[2:0] 350, of the address of the memory location within theprimary memory array 300 is present in the CAM array 310, the CAM array310 presents a 4-bit match identification 355 to the translation array315 to select one of the four lines called offset 370, each of which canhave a value as that shown in Table 1. In one or more embodiments of thepresent invention, the match identification 355 is one-hot encoded,meaning the possible combinations are {0001, 0010, 0100, and 1000}. Thetranslation array 315 presents an 8-bit offset 370 to the outputmultiplexer 330 as shown in Table 1. Once configured by the offset 370,the output multiplexer 330, in accordance with Table 1, allows for thereplacement of 8-bits of the 64-bit row provided by the primary memoryarray 300 with 8-bits of data from the redundant data array 320 toproduce 64-bit composite data 385 as described in detail below. One ofordinary skill in the art will recognize that the offset 370 and outputmultiplexer 330 could be configured in a variety of other manners inaccordance with one or more embodiments of the present invention.

TABLE 1 Offset Configuration of Multiplexer. Offset [7:0] ResultingMultiplexer Configuration 00000001 b0/b2/b4/b6/b8/b10/b12/b14 00000010b16/b18/b20/b22/b24/b26/b28/b30 00000100 b1/b3/b5/b7/b9/b11/b13/b1500001000 b17/b19/b21/b23/b25/b27/b29/b31 00010000b32/b34/b36/b38/b40/b42/b44/b46 00100000 b48/b50/b52/b54/b56/b58/b60/b6201000000 b33/b35/b37/b39/b41/b43/b45/b47 10000000b49/b51/b53/b55/b57/b59/b61/b63The CAM array 310 presents the resource identification 360 to theredundant data array 320. The resource identification 360 could be thematch identification 355. The redundant data array 320 utilizes theresource identification 360 to select one of the four resources of theredundant data array 320. The redundant data array 320 utilizes aportion, ADDR[9:3] 340, of the address of the memory location within theprimary memory array 300 corresponding to the selected resource tooutput an 8-bit line of data 380 to the output multiplexer 330 inaccordance with the read operation. The output multiplexer 330 utilizesthe offset 370, 64-bits of data 365 from the primary memory array, and8-bits of data 380 from the redundant data array 320, to output 64-bitcomposite data 385. Composite data 385 is composed of data 365 or data365 with 8-bits selectively replaced with data 380 in accordance withthe offset 370 provided to the input/output multiplexer 325.

In the case of the write operation, data 365 is input directly to theprimary memory array 300 and composite data 385 is input to the inputmultiplexer 335 in accordance with the address, ADDR[9:3] 340, ADDR[2:0]345, and WAY[2:0] 350, of a memory location within the primary memoryarray 300. Composite data 385 is data 365 for the purpose of the writeoperation. If a portion, ADDR[2:0] 345 and WAY[2:0] 350, of the addressof the memory location within the primary memory array 300 is present inthe CAM array 310, the CAM array 310 presents a match identification 355to the translation array 315 and a resource identification 360 to theredundant data array 320. The translation array 315 utilizes the matchidentification 355 to present an offset 370 to the input multiplexer335. The input multiplexer 335 utilizes the offset 370 to selectivelyoutput one of eight sets of 8-bits of composite data 385 to theredundant data array 320. The redundant data array 320 utilizes theresource identification 360 and a portion, ADDR[9:3] 340, of the addressof the memory location within the primary memory array 300 to input data380 from the input multiplexer 335 to the redundant array 320 inaccordance with the write operation.

FIG. 4 shows an apparatus for row redundancy of a memory array inaccordance with one or more embodiments of the present invention.

A primary memory array 400 is comprised of a plurality of memory cells.The primary memory array 400 could be organized as a 1024-line,64-bits-per-line, 8-way cache array. The primary memory array 400 couldbe logically divided into a plurality of sub-blocks 402 of 128-lines,128-bits-per-line arrays. One or more memory cells of the primary memoryarray 400 may be defective. Thus, a redundant array 405 comprised of aCAM array 410, a translation array 415, and a redundant data array 420and an input/output multiplexer 425 is also included.

The CAM array 410 is organized as a 4-line, 11-bits-per-line array. TheCAM array 410 is configured to store defective memory cell locationswithin the primary memory array 400 and other data necessary as part ofthe redundancy scheme described in detail below. The translation array415 is organized as a 4-line, 4-bits-per-line array in a one hot encodedconfiguration. The translation array 415 is configured to store offset470 in accordance with the defective memory cell locations stored in theCAM array 410. As such, the translation array 415 provides an offset 470to the input/output multiplexer 425 that selects one of four sets of16-bits in the 64-bit row. The translation array 415 could be a registerfile. The redundant data array 420 is organized as a 4-resource,4-lines-per-resource, 16-bits-per-line array. An input/outputmultiplexer 425 is comprised of an input multiplexer 435 and an outputmultiplexer 430. One of ordinary skill in the art will appreciate thatthe primary memory array 400, sub-blocks 402, CAM array 410, translationarray 415, and redundant data array 420 could be organized in variousother manners in accordance with one or more embodiments of the presentinvention.

An address of a memory location within the primary memory array 400 iscomprised of 13-bits that could be logically divided into three groups,ADDR[9:3] 440, ADDR[2:0] 445, and WAY[2:0] 450, to clarify the operationof one or more embodiments of the present invention. The 10-bitsrepresented by ADDR[9:3] 440 and ADDR[2:0] 445 can uniquely identify oneof the 1024 lines of the primary memory array 400. The 3-bitsrepresented by WAY[2:0] 450 can uniquely identify one of the eight waysof the primary memory array 400. The address, ADDR[9:3] 440, ADDR[2:0]445, and WAY[2:0] 450, of the memory location within the primary memoryarray 400 is presented to the primary memory array 400 as part of theread or write operation. The address, ADDR[9:3] 440, ADDR[2:0] 445, anda portion of WAY[2:0] 450, of a memory location within the primarymemory array 400 is presented to the CAM array 410 as part of the reador write operation. A portion, part of WAY[2:0] 450, of the address of amemory location within the primary memory array 400 and resourceidentification 460 is presented to the redundant data array 420 as partof a read or write operation.

In the ease of the read operation, the primary memory array 400 outputs64-bits of data 465 to the output multiplexer 430 in accordance with theaddress, ADDR[9:3] 440, ADDR[2:0] 445, and WAY[2:0] 450, of the memorylocation within the primary memory array 400. If the address, ADDR[9:3]440, ADDR[2:0] 445, and WAY[2:0] 450, of the memory location within theprimary memory array 400 is present in the CAM array 410, the CAM array410 presents a 4-bit match identification 455 to the translation array415 to select one of the four lines called offset 470, each of which canhave a value as that shown in Table 2. In one or more embodiments of thepresent invention, the match identification 455 is one-hot encoded,meaning the possible combinations are {0001, 0010, 0100, and 1000}. Thetranslation array 415 presents a 4-bit offset 470 to the outputmultiplexer 430. Once configured by the offset 470, the outputmultiplexer 430, in accordance with Table 2, allows for the replacementof 16-bits of the 64-bit row provided by the primary memory array 400with 16-bits of data from the redundant data array 420 to produce 64-bitcomposite data 485 as described in detail below. One of ordinary skillin the art will recognize that the offset 470 and multiplexer 430 couldbe configured in a variety of other manners in accordance with one ormore embodiments of the present invention.

TABLE 2 Offset Configuration for Multiplexer. Offset[3:0] ResultingMultiplexer Configuration 0001 b0/b2/b4/b6/b8/b10/b12/b14b16/b18/b20/b22/b24/b26/b28/b30 0010 b1/b3/b5/b7/b9/b11/b13/b15b17/b19/b21/b23/b25/b27/b29/b31 0100 b32/b34/b36/b38/b40/b42/b44/b46b48/b50/b52/b54/b56/b58/b60/b62 1000 b33/b35/b37/b39/b41/b43/b45/b47b49/b51/b53/b55/b57/b59/b61/b63The CAM array 410 presents the resource identification 460 to theredundant data array 420. The resource identification 460 could be thematch identification 455. The redundant data array 420 utilizes theresource identification 460 to select one of the four resources of theredundant data array 420. The redundant data array 420 utilizes aportion, part of WAY[2:0] 450, of the address of the memory locationwithin the primary memory array 400 corresponding to the selectedresource to output a 16-bit line of data 480 to the output multiplexer430 in accordance with the read operation. The output multiplexer 430utilizes the offset 470, 64-bits of data 465 from the primary memoryarray, and 16-bits of data 480 from the redundant data array 420, tooutput 64-bits composite data 485. Composite data 485 is composed ofdata 465 or data 465 with 16-bits selectively replaced with data 480 inaccordance with the offset 470 provided to the input/output multiplexer425.

In the case of the write operation, data 465 is input directly to theprimary memory array 400 and composite data 485 is input to the inputmultiplexer 435 in accordance with the address, ADDR[9:3] 440, ADDR[2:0]445, and WAY[2:0] 450, of a memory location within the primary memoryarray 400. Composite data 485 is data 465 for the purpose of the writeoperation. The input multiplexer 435 outputs data 465 to the primarymemory array 400 in accordance with the address, ADDR[9:3] 440,ADDR[2:0] 445, and WAY[2:0] 450, of the memory location within theprimary memory array 400. If the address, ADDR[9:3] 440, ADDR[2:0] 445,and WAY[2:0] 450, of the memory location within the primary memory array400 is present in the CAM array 410, the CAM array 410 presents a matchidentification 455 to the translation array 415 and a resourceidentification 460 to the redundant data array 420. The translationarray 415 utilizes the match identification 455 to present an offset 470to the input multiplexer 435. The input multiplexer 435 utilizes theoffset 470 to selectively output one of four groups of 16-bits ofcomposite data 485 to the redundant data array 420. The redundant dataarray 420 utilizes the resource identification 460 and a portion, partof WAY[2:0] 450, of the address of the memory location within theprimary memory array 400 to input data 480 from the input multiplexer435 to the redundant data array 420 in accordance with the writeoperation.

FIG. 5 shows an apparatus for column and row redundancy of a memoryarray in accordance with one or more embodiments of the presentinvention.

A primary memory array 500 is comprised of a plurality of memory cells.The primary memory array 500 could be organized as a 1024-line,64-bits-per-line, 8-way cache array. The primary memory array 500 couldbe logically divided into a plurality of sub-blocks 502 of 128-lines,128-bits-per-line arrays. One or more memory cells of the primary memoryarray 500 may be defective. Thus, a column redundant array 505 comprisedof a column CAM array 510, a column translation array 515, and a columnredundant data array 520 is included. In addition, a row redundant array535 comprised of a row CAM array 540, a row translation array 545, and arow redundant array 550 is included. Also, an input/output multiplexer590 is included.

The column CAM array 510 is organized as a 4-line, 6-bits-per-linearray. The column CAM array 510 is configured to store defective memorycell locations within the primary memory array 500 and other datanecessary as part of the redundancy scheme described in detail below.The column translation array 515 is organized as a 4-line,8-bits-per-line array in a one hot encoded configuration. The columntranslation array 515 is configured to store column offset 570 inaccordance with the defective memory cell locations stored in the columnCAM array 510. As such, the column translation array 515 provides ancolumn offset 570 to the input/output multiplexer 590 that selects oneof eight sets of 8-bits in the 64-bit row. The column translation array515 could be a register file. The column redundant data array 320 isorganized as a 4-resource, 128-lines-per-resource, 8-bits-per-linearray.

The row CAM array 540 is organized as a 4-line, 11-bits-per-line array.The row CAM array 540 is configured to store defective memory celllocations within the primary memory array 500 and other data necessaryas part of the redundancy scheme described in detail below. The rowtranslation array 545 is organized as a 4-line, 4-bits-per-line array ina one hot encoded configuration. The row translation array 545 isconfigured to store row offset 575 in accordance with the defectivememory cell locations stored in the row CAM array 540. As such, the rowtranslation array 545 provides a row offset 575 to the input/outputmultiplexer 590 that selects one of four sets of 16-bits in the 64-bitrow. The row translation array 545 could be a register file. The rowredundant data array 550 is organized as a 4-resource,4-lines-per-resource, 16-bits-per-line array.

An input/output multiplexer 590 is comprised of input multiplexer 594and output multiplexer 592. One of ordinary skill in the art willappreciate that the primary memory array 500, column CAM array 510,column translation array 515, column redundant data array 520, row CAMarray 540, row translation array 545, and row redundant array 550 couldbe organized in various other manners in accordance with one or moreembodiments of the present invention.

An address of a memory location within the primary memory array 500 iscomprised of 13-bits that could be logically divided into three groups,ADDR[9:3] 596, ADDR[2:0] 597, and WAY[2:0] 598, to clarify the operationof one or more embodiments of the present invention. The 10-bitsrepresented by ADDR[9:3] 596 and ADDR[2:0] 597 can uniquely identify oneof the 1024 lines of the primary memory array 500. The 3-bitsrepresented by WAY[2:0] 598 can uniquely identify one of the eight waysof the primary memory array 500. The address, ADDR[9:3] 596, ADDR[2:0]597, and WAY[2:0] 598, of the memory location within the primary memoryarray 500 is presented to the primary memory array 500 as part of theread or write operation.

A portion, ADDR[2:0] 597 and WAY[2:0] 598, of the address of a memorylocation within the primary memory array 500 is presented to the columnCAM array 510 as part of the read or write operation. A portion,ADDR[9:3] 596, of the address of a memory location within the primarymemory array 500 is presented to the column redundant data array 520 aspart of a read or write operation.

The address ADDR[9:3] 596, ADDR[2:0] 597, and WAY[2:0] 598 of a memorylocation within the primary memory array 500 is presented to the row CAMarray 540 as part of the read or write operation. A portion, WAY[2:0]598, of the address of a memory location within the primary memory array500 and resource identification 560 is presented to the row redundantdata array 550 as part of a read or write operation.

In the case of the read operation, the primary memory array 500 outputs64-bits of data 565 to the output multiplexer 592 in accordance with theaddress, ADDR[9:3] 596, ADDR[2:0] 597, and WAY[2:0] 598, of the memorylocation within the primary memory array 500.

If a portion, ADDR[2:0] 597 and WAY[2:0] 598, of the address of thememory location within the primary memory array 500 is present in thecolumn CAM array 510, the column CAM array 510 presents an 4-bit columnmatch identification 525 to the column translation array 515 to selectone of the four lines called column offset 570, each of which can have avalue as that shown in Table 1. In one or more embodiments, the columnmatch identification 525 is one-hot encoded, meaning the possiblecombinations are {0001, 0010, 0100, and 1000}. The column translationarray 515 presents an 8-bit column offset 570 to the output multiplexer592 as shown in Table 1. Once configured by the column offset 570, theoutput multiplexer 592, in accordance with Table 1, allows for thereplacement of 8-bits of the 64-bit row provided by the primary memoryarray 500 with 8-bits of data from the column redundant data array 520to produce 64-bit composite data 595 as described in detail below. Oneof ordinary skill in the art will recognize that the column offset 570could be configured in a variety of other manners in accordance with oneor more embodiments of the present invention.

The column CAM array 510 presents the column resource identification 530to the column redundant data array 520. The column resourceidentification 530 could be the column match identification 525. Thecolumn redundant data array 520 utilizes the column resourceidentification 530 to select one of the four resources of the columnredundant data array 520. The column redundant data array 520 utilizes aportion, ADDR[9:3] 596, of the address of the memory location within theprimary memory array 500 corresponding to the selected resource tooutput 8-bits of data 580 to the output multiplexer 592 in accordancewith the read operation. The output multiplexer 592 utilizes the columnoffset 570, 64-bits of data 565 from the primary memory array 500, and8-bits of column data 580 from the column redundant data array 520, tooutput 64-bits composite data 595. Composite data 595 is composed ofdata 565 or data 565 with 8-bits selectively replaced with column data580 in accordance with the column offset 570 provided to theinput/output multiplexer 590.

If the address, ADDR[9:3] 596, ADDR[2:0] 597, and WAY[2:0] 598, of theaddress of the memory location within the primary memory array 500 ispresent in the row CAM array 540, the row CAM array 540 presents a 4-bitrow match identification 555 to the row translation array 545 to selectone of the four lines called row offset 575, each of which can have avalue as that shown in Table 2. In one or more embodiments, the rowmatch identification 555 is one-hot encoded, meaning the possiblecombinations are {0001, 0010, 0100, and 1000}. The row translation array545 presents a 4-bit row offset 575 to the output multiplexer. Onceconfigured by the row offset 575, the output multiplexer 592, inaccordance with Table 2, allows for the replacement of 16-bits of the64-bit row provided by the primary memory array 500 with 16-bits of rowdata from the row redundant data array 550 to produce 64-bit compositedata 595 as described in more detail below. One of ordinary skill in theart will recognize that row offset 575 and output multiplexer 592 couldbe configured in a variety of other manners in accordance with one ormore embodiments of the present invention.

The row CAM array 540 presents the row resource identification 560 tothe row redundant data array 550. The row resource identification 560could be the row match identification 555. The row redundant data array550 utilizes the row resource identification 560 to select one of thefour resources of the row redundant array 550. The row redundant dataarray 550 utilizes a portion, part of WAY[2:0] 598, of the address ofthe memory location within the primary memory array 500 corresponding tothe selected resource to output a 16-bit line of row data 585 to theoutput multiplexer 592 in accordance with the read operation. The outputmultiplexer 592 utilizes the row offset 575, 64-bits of data 565 fromthe primary memory array, and 16-bits of row data 585 from the rowredundant data array 550, to output 64-bits composite data 595.Composite data 595 is composed of data 565 or data 565 with 16-bitsselectively replaced with row data 585 in accordance with the row offset575 provided to the input/output multiplexer 590.

One of ordinary skill in the art will appreciate that data from thecolumn redundant data array and the row redundant data array could beoutput as part of the same read operation in accordance with one or moreembodiments of the present invention. In that case, composite data 595could be composed of data 565 with 8-bits selectively replaced withcolumn data 580 and 16-bits selectively replaced with row data 585.

In the case of a write operation, data 565 is input directly to theprimary memory array 500 and composite data 595 is input to the inputmultiplexer 594 in accordance with the address, ADDR[9:3] 596, ADDR[2:0]597, and WAY[2:0] 598, of a memory location within the primary memoryarray 500.

If a portion, ADDR[2:0] 597 and WAY[2:0] 598, of the address of thememory location within the primary memory array 500 is present in thecolumn CAM array 510, the column CAM array 510 presents a column matchidentification 525 to the column translation array 515 and a columnresource identification 530 to the column redundant data array 520. Thecolumn translation array 515 utilizes the column match identification525 to present a column offset 570 to the input multiplexer 594. Theinput multiplexer 594 utilizes the column offset 570 to selectivelyoutput one of the eight sets of 8-bits of composite data 595 to thecolumn redundant array 520. The column redundant data array 520 utilizesthe column resource identification 530 and a portion, ADDR[9:3] 596, ofthe address of the memory location within the primary memory array 500to input column data 580 from the input multiplexer 594 to the columnredundant data array 520 in accordance with the read operation.

If the address, ADDR[9:3] 596, ADDR[2:0] 597, and WAY[2:0] 598, of thememory location within the primary memory array 500 is present in therow CAM array 540, the row CAM array 540 presents a row matchidentification 555 to the row translation array 545 and a row resourceidentification 560 to the row redundant data array 550. The rowtranslation array 545 utilizes the row match identification 555 topresent a row offset 575 to the input multiplexer 594. The inputmultiplexer 594 utilizes the row offset 575 to selectively output one offour groups of 16-bits of composite data 595 to the row redundant dataarray 550. The row redundant data array 550 utilizes the row resourceidentification 560 and a portion, part of WAY[2:0] 598, of the addressof the memory location within the primary memory array 500 to input rowdata 585 from the input multiplexer 594 to the row redundant array 550in accordance with the write operation.

One of ordinary skill in the art will appreciate that data from thecolumn redundant data array and the row redundant data array could beinput as part of the same write operation in accordance with one or moreembodiments of the present invention.

FIG. 6 shows a method for configuring a redundant array for redundancyof a memory array in accordance with one or more embodiments of thepresent invention.

In S1, a defective memory location within a primary memory array isidentified. A defective memory location means a memory location that isdefective from an inherent defect incurred during the fabricationprocess or a memory location that fails to meet minimum electricalrequirements. A defective memory cell could be identified through theuse of a Built-In Self Test (BIST) mechanism within the device thatcontains the memory array. One of ordinary skill in the art willappreciate that a defective memory cell could be identified throughvarious other manners in accordance with one or more embodiments of thepresent invention.

In S2, an address of the defective memory location within the primarymemory array is stored in a CAM array. One of ordinary skill in the artwill appreciate that the CAM array is an associative array in which thearray is addressed by search data. In this case, the search data is theaddress of the defective memory location within the primary memoryarray.

In S3, a match identification corresponding to the address of thedefective memory location within the primary memory array is stored inthe CAM array. Thus, when an address of a defective memory locationwithin the primary memory array is presented to the CAM array, if theaddress is present in the CAM array, the CAM array returns thecorresponding match identification.

In S4, an offset corresponding to the match identification is stored ina translation array.

One of ordinary skill in the art will appreciate that steps S1 throughS4 could be repeated as necessary to identify all defective memorylocations within the primary memory array.

FIG. 7 shows a method for memory redundancy in accordance with one ormore embodiments of the present invention.

In S1, an address of a memory location within a primary memory array ispresented to the primary memory array. The address is comprised ofenough bits to uniquely identify the memory location within the primarymemory array. One of ordinary skill in the art will appreciate that theaddress is presented as part of a read or write operation.

In S2, the address of the memory location within the primary memoryarray is presented to a redundant array. The redundant array iscomprised of a CAM array, a translation array, and a redundant array.One of ordinary skill in the art will appreciate that the address ispresented as part of the read or write operation.

In S3, a determination is made as to whether the address of the memorylocation within the primary memory array corresponds to a defectivememory location within the primary memory by the presence of the addressof the memory location within the primary array in the CAM array. One ofordinary skill in the art will appreciate that the address of defectivememory locations within the primary array could be configured in the CAMarray in accordance with the method shown in FIG. 6.

In S4, an evaluation is made as to whether the address of the memorylocation within the primary array corresponds to the defective memorylocation within the primary memory array stored in the CAM array. One ofordinary skill in the art will appreciate that presenting the address ofthe memory location within the primary array to the CAM array results ina match or not, which could form the basis for the evaluation.

In S5, upon an affirmative evaluation that the address of the memorylocation within the primary array corresponds to the defective memorylocation within the primary memory array stored in the CAM array, theCAM array presents a match identification to the translation array and aresource identification to the redundant data array.

In S6, the translation array presents an offset to the input/outputmultiplexer.

In S7, the input/output multiplexer is configured in accordance with theoffset. The input/output multiplexer could be configured to utilizesome, all, or none of the read or write data from or to the redundantdata array.

In S8, the primary memory array, redundant array, and input/outputmultiplexer are appropriately addressed and configured. Thus, a read orwrite operation in accordance with the location within the primarymemory array is directed to the primary memory array and the redundantdata array.

In S9, upon a negative evaluation that the address of the memorylocation within the primary array corresponds to the defective memorylocation within the primary memory array stored in the CAM array, a reador write operation in accordance with the address of the location withinthe primary memory array is directed to the primary memory array.

FIG. 8 shows an apparatus for column and row redundancy of a memoryarray disposed in a computer system in accordance with one or moreembodiments of the present invention.

A computer system 800 includes several components that are collectivelyused by a user to perform various functions such as, for example,generating a document with a word processor. The user may input data toa computing portion 810 using peripheral devices such as a keyboard 840or a mouse 850. Data may also be provided to the computing portion 810using data storage devices (e.g., a floppy disk, fixed disk, flashdevice, CD, DVD, etc.). The computing portion 810, using memory andother internal components, processes both internal data and dataprovided to the computing portion 810 by the user to generate datarequested by the user. The generated data may be provided to the uservia a display device 820 or a printer 830.

The computing portion 810 typically includes various components such asone or more power supplies, one or more data storage devices, one ormore microprocessors, and one or more circuit boards containingcircuitry required to perform the necessary and requested operations ofthe computer system 800. Those skilled in the art will appreciate thatone or more elements of the computer system 800 may take various otherforms and may be located at a remote location and connected to the otherelements over a network.

Those skilled in the art, having the benefit of this detaileddescription, will appreciate that the method and apparatus for memoryredundancy may be used advantageously to provide redundancy fordefective memory cells within a primary memory array. Advantages of oneor more embodiments of the present invention may include one or more ofthe following.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy is more efficient and flexible becauseit provides soft programmable repair resources. Software may be used toprogram repairs during production testing or anytime during the lifetimeof the product.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy is more efficient and flexible becausethe repair resources may be shared without a fixed address space. Assuch, redundant memory elements may be shared by a larger memory spacethan typical shift register schemes, and as a consequence, improve theyield.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy provides for improved granularity ofrepair. Memory redundancy may be provided for a portion of a memoryarray line instead of replacing the entire memory array line.Additionally, different sections of the memory array line may berepaired by row redundancy, column redundancy, or both.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy may be used advantageously wherein theprimary memory array and redundant array share the same address space.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy may be used advantageously withoutnegatively impacting memory timing or performance.

In one or more embodiments of the present invention, the method andapparatus for memory redundancy may be used advantageously to minimizethe area and routing overhead required to implement a redundancy scheme.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having the benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims.

1. An apparatus for redundancy of a memory array comprising: a primarymemory array comprising a plurality of memory cells wherein one or morememory cells of the primary array are defective; a redundant arraycomprising: a CAM array comprising a plurality of memory cells, whereinthe addresses of the one or more defective memory locations within theprimary array are stored, wherein the CAM array is addressed by theaddresses of the one or more defective memory locations within theprimary memory array, and wherein the CAM array provides a matchidentification to a translation array and a resource identification to aredundant data array, the translation array, wherein an offset thatconfigures an input/output multiplexer is stored, wherein thetranslation array provides the offset to the input/output multiplexer,the redundant data array comprising a plurality of memory cells, whereinone or more memory cells of the redundant data array are used instead ofone or more defective memory cells of the primary array; and theinput/output multiplexer wherein the input/output multiplexerselectively presents data comprised of data from or to the primarymemory array or data from or to the primary memory array and theredundant array.
 2. The apparatus of claim 1, wherein the CAM array andtranslation array are configured prior to the operation of the redundantarray.
 3. The apparatus of claim 1, wherein the resource identificationis the match identification.
 4. The apparatus of claim 1, wherein thetranslation array could be comprised of a register file.
 5. Theapparatus of claim 1, wherein the input/output multiplexer could becomprised of a plurality of multiplexers.
 6. The apparatus of claim 1,wherein the apparatus is disposed in a microprocessor, ASIC, FPGA, orother semiconductor device.
 7. The apparatus of claim 6, wherein theprimary memory array is an instruction or data cache.
 8. The apparatusof claim 6, wherein the microprocessor, ASIC, FPGA, or othersemiconductor device is disposed in a system.
 9. The apparatus of claim7, wherein the semiconductor is disposed in a computer system comprisinga display device, an input device, and a computing apparatus.
 10. Amethod for configuring a redundant array for redundancy of a memoryarray comprising: identifying a defective memory cell within a primarymemory array; storing an address corresponding to the address of thedefective memory cell within the primary memory array in a CAM array;storing a match identification corresponding to the address of thedefective memory cell within the primary memory array in the CAM array;storing a resource identification corresponding to the matchidentification in the CAM array; and storing an offset corresponding tothe resource identification in a translation array.
 11. The method ofclaim 10, wherein the translation array could be comprised of a registerfile.
 12. The method of claim 10, further comprising identifying thedefective memory cell through the use of a built-in self-test (BIST).13. A method for redundancy of a memory array comprising: presenting anaddress of a memory location within a primary memory array to theprimary memory array; presenting the address of the memory locationwithin the primary memory array to a redundant array wherein theredundant array is comprised of a CAM array, a translation array, and aredundant data array; determining whether the address of the memorylocation within the primary memory array corresponds to a defectivememory location within the primary memory array; if the address of thememory location within the primary memory array corresponds to thedefective memory location within the primary memory array, presenting amatch identification from the CAM array to the translation array,presenting a resource identification from the CAM array to the redundantdata array, presenting an offset that corresponds to the resourceidentification from the translation array to an input/outputmultiplexer, configuring the input/output multiplexer in accordance withthe offset, performing a read or write operation in accordance with theaddress of the memory location within the primary memory array to theredundant data array; performing the read or a write operation inaccordance with the address of the memory location within the primarymemory array to the primary memory array; and presenting datacorresponding to the address of the memory location within the primarymemory array in accordance with the read or write operation.
 14. Themethod of claim 13, wherein the resource identification is the matchidentification.
 15. The method of claim 13, wherein the method isutilized for column redundancy.
 16. The method of claim 13, wherein themethod is utilized for row redundancy.
 17. The method of claim 13,wherein the method is utilized for column and row redundancy.
 18. Themethod of claim 13, wherein the address of the memory location comprisesa row address and a column address.
 19. The method of claim 18, whereinthe address of the memory location further comprises a way address. 20.The method of claim 13, wherein the determination is made by thepresenting of the address of the memory location within the primarymemory array to the CAM array.